Naperville Smart Grid Initiative: The Community Advantage

A number of variables contributed to Naperville’s success in developing their smart microgrid. As a public power utility, Naperville had greater control and lower costs of capital and interest than would be the case with a larger utility. Equally important, however, was the foresight shared by the Mayor, City Council, and majority of the community that pushed the limits of technology to achieve something truly innovative and ahead of its time.

Over a span of 17 years, the Naperville department of public utilities staff has been guided by a mantra of continuous improvement and a constant search for new technologies and system design approaches. They recognized the limitations inherent in systems with radial designs — where, because electricity is only connected at the source of distribution, there are few options for real-time correction in case of a failure. Despite the fact that this design was most common, the Naperville team embraced a loop configuration, where electricity is interconnected throughout the system, as it gives electricity an alternate path to follow in case of a disturbance and is thereby much more reliable. Underground infrastructure is appealing for aesthetic reasons as well as reliability, but outages take longer to detect because they are not visible. Automation technology helped counter this limitation as it can instantly locate and isolate the fault.

A look at the reliability metrics demonstrates Naperville’s success in creating a significantly more reliable system. One standard reliability measurement in the U.S. is known as SAIDI, which stands for System Average Interruptible Duration Index (SAIDI) and shows the average outage duration for each customer served. In 1992, Naperville’s SAIDI measurement was 120 minutes. In 2010, it was down to an impressive 18 minutes.

Not satisfied with eliminating outages, Naperville also set the bar high for the integration of renewable energy sources. The new automated grid allows for two way flow of power and net metering of consumer installed low carbon generation (e.g. solar power). When their new substations were being developed, they were built so that solar panels could be installed on the substation rooftops once the technology and funding was ready to support it. This again demonstrated the foresight that has guided the smart grid project to its success.

Today, the current system features the following advanced technology, from leading providers both within and outside the state: